Examples of hearing assistance devices, also referred to herein as hearing instruments, include both prescriptive devices and non-prescriptive devices. Examples of hearing assistance devices include, but are not limited to, hearing aids, headphones, assisted listening devices, and earbuds.
Modern hearing instruments are typically equipped with a feedback cancellation circuit which helps prevent oscillations due to feedback from the receiver output to the microphone input. The feedback canceller is designed to adapt slowly on signals that are time stationary over relatively long intervals compared with speech. However, if the hearing instrument is used in two-way communication system, the feedback canceller does not address echo produced by the acoustic and/or electrical feedback of signals.